Vehicle / Diluent
Bacteriostatic Water
Last updated
Sterile water containing 0.9% benzyl alcohol, a preservative that stops bacteria multiplying. It is used to dissolve lyophilised powder in a vial that will be entered more than once. Bacteriostatic means growth-inhibiting, not killing. That preservative is the reason a punctured vial has a usable window at all.
Why it matters here
On this site the beyond-use date is derived from the vehicle and the storage class rather than typed in by hand. Bacteriostatic water plus refrigeration is what produces the 28-day window from first puncture, and changing either input changes the date with it.
What it is not
The 0.9% on a bacteriostatic water label is benzyl alcohol; the 0.9% on a saline label is sodium chloride. They are different substances that happen to share a number, and bacteriostatic water is not saline, containing no salt and being hypotonic.
Also called
- bacteriostatic water
- bac water
- bacteriostatic
- bw
Bac water and BW are informal shorthand from forums and vendor listings. Bacteriostatic on its own names the preservative property, not a brand.
Compounds carrying this term
None on file yet. This term is in the controlled vocabulary but no compound record currently uses it — which is a statement about our coverage, not about the term.